1. Field of the Invention
The invention relates to an implantable cardiac stimulator for cardiac resynchronization therapy (CRT) on a heart. The cardiac stimulator may be a cardiac pacemaker or an implantable cardioverter/defibrillator (ICD) or a combination of the two that is capable of stimulating both ventricles of a heart.
2. Description of the Related Art
Such a cardiac stimulator typically has at least one right ventricular sensing unit and one right ventricular stimulation unit as well as one left ventricular sensing unit and one left ventricular stimulation unit. During operation of the cardiac stimulator, these units are each connected to electrodes implanted at suitable locations in the heart. The electrode line with the electrodes for detecting electric potentials in the left ventricle of the heart and for delivering left ventricular stimulation pulses is typically part of a left ventricular electrode line, which is implanted through the coronary sinus of the heart and therefore is also referred to as a coronary sinus electrode line. The electrodes for detecting electric potentials in the right ventricle and for delivering right ventricular stimulation pulses are typically attached to a right ventricular electrode line whose distal end protrudes into the apex of the right ventricle. At their proximal end, the electrode lines are typically connected to a corresponding cardiac stimulator via standardized plug connections.
The typical stimulation modes of a right ventricular cardiac stimulator such as VVI, VVD or DDD, for example, may be assumed to be known. The same thing is also true of the delivery of stimulation pulses only in case of need (demand pacemaker) in which delivery of a stimulation pulse to a particular chamber of the heart is suppressed when a particular characteristic action (intrinsic contraction) of the respective heart chamber has been detected in a corresponding escape interval via a sensing unit of the cardiac stimulator assigned to this ventricle of the heart. These essentially known concepts may also be implemented with the cardiac stimulator described here.